In general, at a pneumatic tire at a time of cornering, a ground contact pressure of the pneumatic tire is higher at the vehicle outer side than at the vehicle inner side. Therefore, to improve cornering characteristics, an increase in tread stiffness at a tire mounting outer side is called for. Meanwhile, it is also necessary to consider drainage characteristics during running on wet road surfaces. Accordingly, forming narrow circumference direction grooves at the tire mounting outer side relative to main drainage grooves has been proposed (for example, see Patent Documents 1 to 4).
However, drainage cannot be considered satisfactory from just the formation of narrow circumference direction grooves, and technologies to further improve drainage are being called for.
Patent Document 1: Japanese Patent Application Laid-Open (JP-A) No. 2009-006833
Patent Document 2: JP-A No. 2010-058781
Patent Document 3: JP-A No. 2000-043514
Patent Document 4: JP-A No. 2006-151029